Jon Børre Ørbæk Roland Kallenborn Ingunn Tombre Else Nøst Hegseth Stig Falk-Petersen Alf Håkon Hoel Editors Arctic Alpine Ecosystems and People in a Changing Environment with 86 Figures and 10 Tables Dr. Jon Børre Ørbæk Dr. Else N. Hegseth Norwegian Polar Institute Norwegian College of Fishery Science Svalbard University of Tromsø P.O.Box 505 Breivika 9171 Longyearbyen 9037 Tromsø Norway Norway Dr. Roland Kallenborn Dr. Stig Falk-Petersen Norwegian Institute Norwegian Polar Institute for Air Research Polar Environmental Centre Polar Environmental Centre 9296 Tromsø 9296 Tromsø Norway Norway Dr. Ingunn Tombre Dr. Alf H. Hoel Norwegian Institute University of Tromsø for Nature Research Department of Political Science Polar Environmental Centre Breivika 9296 Tromsø 9037 Tromsø Norway Norway Cover photograph: Bjørn Fossli Johansen, Norwegian Polar Institute, 2005 Library of Congress Control Number: 2006935137 ISBN-10 3-540-48512-4 Springer Berlin Heidelberg New York ISBN-13 978-3-540-48512-4 Springer Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. 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Kirchner, Heidelberg Production: Almas Schimmel Typesetting: camera-ready by authors Printing: Krips bv, Meppel Binding: Stürtz AG, Würzburg Printed on acid-free paper 30/3141/as 5 4 3 2 1 0 18 Modeling of long-range transport of contaminants from potential sources in the Arctic Ocean by water and sea ice Vladimir Pavlov Norwegian Polar Institute, Polar Environmental Centre, N-9296, Tromsø, Norway, e-mail: [email protected] 18.1 Introduction The geographical position and climatic features of the Arctic seas mean that their ecological balance is sensitive to disturbance by inputs of man- made pollutants. The Arctic seas represent zones where pollutants natu- rally accumulate and pollutants are transported between regions where there is active exploitation of natural resources and pollution, and the ecol- ogically clean regions of the central Polar Basin. The processes involved in the transport, transformation and accumulation of contaminants from dif- ferent possible sources are important in assessing whether we are to fore- cast the fate of potential pollutant releases. These sources and potential sources are described by several reports and papers (Yablokov Commis- sion Report 1993; Aarkrog 1993; Pavlov and Pfirman 1995; Duursma and Carroll 1996; ANWAP 1997; AMAP 1997; AMAP 1998; Champ et al. 1998; Yablokov 2001). In some Arctic seas, such as the Barents and Kara seas, there were earlier local sources of anthropogenic origin, connected with the nuclear trials at the test site of Novaya Zemlya and dumping of radioactive waste over their areas. Extensive dumping of nuclear materials in the Kara and Barents seaɵ marine environment is listed in the Yablokov Commission Report (1993) and in Yablokov (2001). Low level liquid ra- dioactive wastes are stored in the following regions of Russia in large vol- umes: by the northern fleet in the Kola Peninsula in the Murmansk and Severodvinsk regions, and by the Pacific fleet in the Russian Far East in the naval ship yards at Vladivostok. The combined capacity of all Northern Fleet containers amounts to 10,000 m3 and annual production is estimated to be about 20,000 m3. Approximately 30 to 40,000 m3+ of solid radioac- tive waste is stored at different sites in the Russian Far East and Northwest 330 Vladimir Pavlov (ANWAP 1997; AMAP 1998; Champ et al. 1998). The discharges of fresh water from the large Arctic rivers that have huge catchment areas draining water from land areas and industrial zones also contribute to the input of pollutants into the Arctic Ocean. Ocean currents and drifting ice are among the most important mecha- nisms of pollutant transport (Nürnberg et al. 1994; Emery et al. (1997); Pfirman et al. 1997; Nilsson 1997; Rigor and Colony 1997; Smith et al. 1998; Smith and Ellis 1999; Zhang et al. 2000; Rigor et al. 2002; Zhang et al. 2003; Pfirman et al. 2004a; Pfirman et al. 2004b). Severe natural condi- tions and the year-round presence of drifting ice make direct full-scale ob- servations of currents difficult and expensive. Numerical modelling, sup- ported and validated by in situ field observations, is therefore the only practical possibility for gaining an understanding of water circulation in the Arctic Ocean on different spatial and temporal scales. Many models describing transport and transformation of various pollutants in the water environment of the Arctic have appeared in recent years inspired by in- creasing anthropogenic effects, especially in coastal zones (Preller and Cheng 1995; Pavlov et al. 1995; Harms 1997; Scott et al. 1997; AMAP 1998; Nies et al. 1999; Harms and Karcher 1999; Harms et al. 2000; Karcher et al. 2004 and others). In these papers, modelling results for the spreading of contaminants from individual sources, mostly located in the Nordic seas and Kara Sea, were discussed. For example, Harms (1997) has described the application of 3-D, baroclinic circulation models to study the dispersal of radioactivity in the Barents and Kara seas. Release is expected to occur at underwater dump sites for radioactive waste in the Kara Sea, used by the former Soviet Union. To cover the wide range of a possible ra- dionuclide dispersion, two different spatial scales were considered: i) the regional scale, which covered the shelves of the Barents and Kara seas and ii) the local scale, which is focused on the bay where some of the dumping took place. The regional-scale model results have suggested that, even for a worst case scenario, the radioactive contamination of Siberian coastal waters would be relatively small compared to observations in other marine systems (e.g. the Baltic Sea and the Irish Sea). Realistic gradual release scenarios show very low concentrations in the central and eastern Kara Sea. Significant contamination of shelf seas such as the Laptev Sea, the Arctic Ocean or the Barents Sea by radioactive waste dispersion from the Kara Sea seems unlikely. Nies et al. (1999) presented a review of results from a joint project car- ried out in Germany in order to assess the consequences to the marine en- vironment from the dumping of nuclear waste in the Kara and Barents seas. The project consisted of experimental work on measurements of ra- dionuclides (137Cs, 90Sr, 239+240Pu, 238Pu, 241Am) in samples from the Arctic 18 Modelling long-range transport of contaminants by water and sea ice 331 marine environment, and numerical modelling of the potential pathways and dispersion of contaminants in the Arctic Ocean. The role of transport by sea ice from the Kara Sea into the Arctic Ocean was assessed. This transport process might be considered as a rapid contribution of pollutants due to entrainment of contaminated sediments into sea ice, followed by export from the Kara Sea by the Transpolar Ice Drift, and subsequent re- lease in the Arctic Ocean in the region of the East Greenland Current. Nu- merical modelling of pollutant dispersion from the Kara and Barents seas was carried out both on a local scale, for the Barents and Kara seas, and for long range dispersion into the Arctic and Atlantic oceans. 3-D baroclinic circulation models were applied to trace the transport of pollutants. Model- ling results show no significant pollution even for worst case scenarios from the radioactive waste dumped in the Kara Sea to other seas in the Arctic or North Atlantic (as in Harms 1997). The results from the disper- sion models suggest that, even for worst case scenarios, the contamination of Arctic waters and North Atlantic areas is relatively minor compared to pre-contamination from Sellafield, or global fallout from nuclear weapon testing in the 1960s. Long range simulations of Sellafield discharges of 137Cs since the 1960s correlates well with measured levels. Harms et al. (2000) investigated the role of Siberian river runoff for the transport of possible river contaminants in the Arctic Ocean. 3-D coupled ice-ocean models of different horizontal resolution were applied to simulate the dis- persion of river water from the Ob, Yenisei and Lena. Circulation model results explain the main pathways and transit times of Siberian river water in the Arctic Ocean. Kara Sea river water clearly dominates in the Siberian branch of the Transpolar Drift, while the water from the Lena dominates in the Canadian Branch. The model confirms that contaminant transport through sediment laden sea ice offers a short and effective pathway for pollutant transport from Siberian rivers to the Barents and Nordic seas. Karcher et al. (2004) have compared the simulated dispersion of 99Tc in surface water from the sources to the Nordic Seas and the Arctic Ocean as calculated by a hydrodynamic model and in assessment box model with field-observations from 1996 to 1999 to study concentrations, pathways and travel times. The observations cover the northern part of the Nordic Seas. The main sources of 99Tc are global fallout from nuclear weapon testing, and discharges from reprocessing plants for spent nuclear fuel in Northwestern Europe.